---
tags:
  - bash
  - howto
---
[[Bash]] [[Parameter subsitution]] [[Null substitution]]

Process substitution connects the output of a command to a file. This enables another command to accept the output of multiple commands as files if it expects files.

An example of this is `diff`, which outputs the difference between two files:
```bash
diff <(ls dirA) <(ls dirB)
```

> Important! Don't but the <() inside quotes.. it will report: cannot find file